I've looked at Dhall before, and never come away with a desire to try it. It's interesting, and definitely has a lot of the right ideas. I'm not convinced functions are necessary.
Also, any language without an official browser JavaScript implementation obviously wasn't created to solve the same problems I'm interested in.
It's hard to take Dhall seriously because it seems like its authors don't take it seriously, and work on it for entertainment. They went through the trouble of creating bindings for five (!!) different languages, and the most popular of them, by a pretty wide margin, is Ruby. I assume Fortran, Delphi, and Idris are next on their list.
Rust and Go are even less popular than Ruby but glad to hear about Java and Python. Either one of them has at least 5x the market penetration of all currently supported languages combined, and at least 10x of all of them but Ruby combined.
Overall language popularity is only one input into how we prioritize programming languages.
The best way I can summarize our prioritization process is that we prioritize in descending over:
* What people are willing to spend their free time to build (I can't order other people to build high-priority bindings and my own free time is already accounted for by improving Haskell bindings that power a lot of shared tooling such as the language server)
* Bindings specific to DevOps use cases (e.g. Go / Python / Ruby / Nix / JSON / YAML), since they are the dominant languages and formats in this space)
* Bindings that can be used to create derived bindings (e.g. Rust, which can then be used to create a binding in any language that can bind to C. In fact, this is how the upcoming Python bindings work. See: https://pypi.org/project/dhall/)
* Bindings that users request (We have a yearly survey where we ask users to inform the direction of the ecosystem. Python was the most requested language in the most recent survey)
* Overall language popularity (as the final tiebreaker)
So I hope this illustrates that there is a lot more that goes into these decisions beyond just which language is the most popular and we're not being obtuse or dilettantes just because we haven't gotten to a specific language, yet.
PureScript corresponds pretty closely to JavaScript in terms of the code it generates, so once we have a PureScript binding it shouldn't be hard to generate lean JavaScript bindings from that. Also, more people requested the PureScript bindings over the JavaScript bindings anyway in our most recent yearly survey:
> Dhall is a programmable configuration language that you can think of as: JSON + functions + types + imports
https://dhall-lang.org